Final answer:
Pilocarpine ophthalmic drops constrict the pupil and cause the ciliary muscle to contract, leading to the drainage of aqueous humor and a reduction in intraocular pressure.
Step-by-step explanation:
Pilocarpine ophthalmic drops, when used to treat primary open-angle glaucoma, work by constricting the pupil (miosis) and causing the ciliary muscle to contract. This contraction opens perforations at the base of the cornea, allowing for the drainage of aqueous humor from the anterior compartment of the eye. By facilitating the drainage of aqueous humor, pilocarpine helps to reduce intraocular pressure associated with glaucoma.